JP4632423B2 - POSITION CONTROL DEVICE, POSITION CONTROL METHOD, AND OPTICAL DEVICE - Google Patents

Description

  The present invention relates to a position control device and a position control method suitable for, for example, automatic focusing control of an imaging device, and an optical device including the position control device.

  In recent years, in an imaging apparatus such as a digital still camera or a video camera, high accuracy on the order of several μm has been required for lens positioning control as the number of pixels of an imaging element such as a CCD is increased and the size is reduced. Yes. This is because, as the number of pixels of the image sensor increases and the size of the image sensor decreases, the out-of-focus blur of the captured image due to the positioning error of the lens becomes more conspicuous. That is why.

  An optical encoder is one of sensors that detect the position of a lens in order to achieve such high positioning accuracy. The optical encoder basically has a main scale on which a first optical grating in which a grating that transmits light and a grating that does not transmit light are arranged at a constant period, and a second optical grating that is similar to the main scale. Formed with an index scale, a light source for irradiating the main scale with light, and a light receiving element that transmits or reflects the optical grating of the main scale and receives the light transmitted through the optical grating of the index scale. The At this time, there is a configuration that also serves as an index scale using a light receiving element array. Various optical encoders of this type have already been proposed (for example, Patent Document 1).

  The encoder configured as described above is called an incremental type, and a multi-phase sinusoidal signal output from the encoder as the scale moves is converted into a pulse signal by a signal processing circuit. The amount of movement is detected. Therefore, since this incremental type can only detect the relative movement amount, in order to detect the absolute position and the absolute angle, a separate sensor for detecting the absolute position as the origin position (reference position) is required. And installation space may increase.

On the other hand, the following are proposed as an optical encoder capable of detecting the absolute position and the absolute angle (e.g., Patent Document 2).

  FIG. 7 is a diagram showing a means for detecting an origin position in an incremental encoder that performs angle detection using a circular optical scale. In this example, in order to detect the origin position, the transmittance of the pattern of the optical scale 101 is changed. The transmittance of the region 102 is approximately 100%, while the region 103, 104, 105. The transmittance is lowered.

FIG. 8 is a signal change obtained when a portion where the transmittance of the optical scale 101 changes when the scale is used, and 106 and 107 are encoder output signals (analogues) obtained from the sensor. Two-phase signal). At this time, since the signal amplitude of the encoder output signal becomes smaller as the transmittance of the optical scale 101 gradually decreases, the origin position is detected by detecting this change. With such a configuration, an absolute angle (absolute position) can be detected without separately providing a sensor for detecting the origin position, and an increase in cost and sensor installation space can be avoided.

  Up to this point, the origin detection in the optical encoder has been described. Next, the conventional technique for performing highly accurate position detection on the order of several μm based on a plurality of sine wave signals output from the optical encoder will be described. To do.

  As described above, when a multi-phase sinusoidal signal output from the optical encoder is converted into a pulse signal, the resolution of one pulse depends on the arrangement density of the optical grating on the scale, and is about several tens of μm. is there. Therefore, in order to detect the position with higher accuracy, a phase having a signal component with excellent linearity is selected from the sine wave signal components of multiple phases, and an operation for interpolating the signal component is performed. A method for detecting the position based on the result has been proposed (for example, Patent Document 3).

  Since the calculation method of the position by the interpolation calculation is well known, a detailed description thereof will be omitted, and only the conventional technique relating to the correction of the encoder output signal for performing the interpolation calculation will be described below.

  In general, the outputs of a plurality of phases of an optical encoder often have different amplitudes and levels of amplitude centers as shown in FIG. Therefore, since the accuracy cannot be sufficiently obtained when the position is calculated by the interpolation calculation as described above, the correction process of the encoder output data is performed so that the amplitude and the amplitude center are aligned as shown in FIG. 10, for example. .

This correction processing is performed as follows. That is, the lens as the measurement object is moved for one cycle or more of the sine wave output of the encoder, and the encoder output signal is taken into the position calculation microcomputer via the A / D converter. Calculated gain offset adjustment value used for more correction the maximum and minimum values of the output signal data taken, correction processing by processing the output signal data to the amplitude and the amplitude center aligned on the basis of the adjustment value Is done.

  Specifically, assuming that the maximum value of the output signal data is MAX and the minimum value is MIN, the adjustment values GAIN and OFFSET are calculated by Expressions (1) and (2), respectively. Note that RANGE in Equation (1) is the dynamic range of the adjusted data.

  The corrected encoder output data OUTPUT is obtained by applying the correction formula of Formula (3) to the output signal data SIG using the GAIN and OFFSET obtained here.

By performing interpolation using the encoder output data corrected in this way, it is possible to realize lens position detection and lens positioning control with high accuracy required for the imaging apparatus.
JP2003-161645 (paragraph numbers 0024 to 0032, FIG. 1 and the like) JP-A-10-318790 (paragraph numbers 0011 to 0020, FIG. 1, etc.) Patent No. 03008503 (paragraph numbers 0008 to 0013, FIG. 1 etc.)

  Here, when the position calculation processing method described above and the origin position detection method were combined, and a method for controlling the absolute position of the lens with high accuracy without increasing cost and installation space was being studied, imaging The problem of performance degradation as a device became apparent.

  More specifically, as already shown in FIG. 9, the signal amplitude of the encoder signal changes abruptly at the origin position, and accordingly, the signal amplitude at the position where the maximum value of the signal is obtained and the position where the minimum value is obtained. Therefore, GAIN obtained by Equation (1) has a value different from the accurate signal amplitude. Similarly, the maximum and minimum values of the signal are asymmetrical with respect to the amplitude center as the signal amplitude changes, so that OFFSET obtained by Equation (2) is also shifted from the signal amplitude center. As a result, an error occurs in the correction process of the output signal data of the encoder, and the accuracy of position detection by the interpolation calculation is reduced in the vicinity of the origin position.

  In other words, when the conventional origin position detection method and the position calculation processing method are combined, the lens position control accuracy decreases near the origin position due to a decrease in the position detection accuracy near the origin position, resulting in out-of-focus when shooting. In some cases, the performance of the imaging device is degraded.

  The present invention has been made based on such circumstances, and an object of the present invention is to prevent the performance degradation of the position control device due to the lowered position detection accuracy of the position control object near the origin position described above. To do. Another object of the present invention is to prevent performance degradation as an imaging device when a position control device is used to control the position of a lens in the imaging device.

The position control device of the present invention includes a scale on which a periodically changing pattern is formed, an encoder that outputs a sinusoidal signal by moving relative to the scale according to the movement of the position control object, Control means for controlling the position of the controlled object, and the scale is configured to change the amplitude of the output signal of the encoder, and a first region configured to make the amplitude of the output signal of the encoder constant. The position control object is a lens of the photographing optical system, and the first region corresponds to the optical effective range of the photographing optical system in which the lens can be moved during photographing. a regions, the control means based on the output signal of the encoder generated by the second region, and detects the origin position in the position control of the position control object, the detected home position And detecting the absolute position of the position control object using.

The position control method of the present invention includes a scale on which a periodically changing pattern is formed, and an encoder that outputs a sinusoidal signal by moving relative to the scale according to the movement of the position control object. A position control device having a first area in which the scale is configured to make the amplitude of the output signal of the encoder constant, and a second area configured to change the amplitude of the output signal of the encoder; A position control method used for controlling the position of a position control object , wherein the position control object is a lens of a photographing optical system, and the first region allows the lens to move during photographing. a corresponding to the optically effective range of the photographing optical system area, based on an output signal of the encoder generated by the second region, detects the origin position in the position control of the position control object A first step of using the detected home position in a first step, and having a second step of detecting the absolute position of the position control object.

According to the present invention, the amplitude of the output signal of the encoder is made constant using the first region provided in the scale, and the absolute position of the position control object is detected based on this signal. Accurate position detection can be performed. Further, by changing the amplitude of the output signal of the encoder by using a second region provided on the scale, it can detect the home position easily based on this signal.

  Examples of the present invention will be described below.

  A case where the position control apparatus according to the first embodiment of the present invention is applied to lens position control in an imaging apparatus will be described below with reference to the accompanying drawings.

  FIG. 1 is a block diagram illustrating a configuration of an imaging apparatus including a position control device, for example, a digital video camera or a digital still camera. In the figure, reference numeral 201 denotes a part of a lens (focus lens) of the photographing optical system, which is a position control object that can move in the optical axis direction (the arrow direction in FIG. 1). It is supported and provided inside the lens barrel 202.

  The lens support section 202a is slidable by receiving a driving force from a lens driving motor 203 as a driving source, and the lens 201 is configured to be movable in the optical axis direction.

  In the figure, reference numeral 204 denotes an image sensor such as a CCD sensor or a CMOS sensor, which is a photoelectric conversion element. The light flux from the subject incident through the lens 201 forms an image on the image sensor 204, and the subject image (optical image) is converted into an electrical signal. The image signal read from the image sensor 204 is subjected to predetermined image processing such as forming a luminance signal or a color signal in the image processing circuit 205 to generate a color image signal (image data).

  The image signal generated in this way is displayed on a liquid crystal display unit provided in the imaging apparatus, or stored in a storage medium such as a magnetic tape or an image storage memory.

  In FIG. 1, the lens 201 is shown as a single lens, but in general, the photographing optical system is composed of a plurality of lenses. Further, the imaging apparatus includes a light amount adjustment unit (for example, including an aperture unit) that adjusts the amount of light incident on the image plane. Further, a zoom mechanism (including a zoom lens) that changes the focal length of the photographing optical system may be provided.

  As shown in FIGS. 1 and 2, an optical scale 301 extending in the optical axis direction is supported and provided on a scale support portion 304 fixed to a lens support portion 202a. That is, the optical scale 301 is configured to slide in the optical axis direction integrally with the lens 201 as the lens 201 moves.

  The surface of the optical scale 301 is provided with a plurality of optical gratings 302 having a predetermined reflectance arranged at a constant period, for example, at equal intervals along the optical axis direction. Further, in order to detect the origin position (reference position) of the lens 201, a discontinuous region 302a having different optical characteristics is provided on the surface of the optical scale 301.

  In the discontinuous region 302a, the reflectances of a part of the plurality of optical gratings 302 provided on the surface of the optical scale 301, for example, three adjacent optical gratings 302 are different from each other. Further, the reflectance of the optical grating 302 in the discontinuous region 302a is different from the reflectance of the other optical gratings 302 outside the discontinuous region 302a.

For example, the reflectance of the optical grating 302 in the discontinuous region 302a can be changed by applying black markings to the optical scale.

  That is, the optical scale 301 includes a first region in which a plurality of optical gratings 302 having a predetermined reflectance are arranged in the optical axis direction, and a plurality of optical gratings 302 having different reflectances in the optical axis direction. And a second region (discontinuous region 302a).

  Here, the plurality of optical gratings 302 in the first region have substantially the same reflectance. The first and second regions are configured as a periodic signal generator and a discontinuous signal generator, respectively.

  For example, an optical sensor 303 is fixed to the inner peripheral surface of the lens barrel 202 so as to face the surface of the optical scale 301. The optical sensor 303 includes a light emitting unit (not shown) that irradiates light on the surface of the optical scale 301 and a light receiving unit that receives the light reflected by the optical scale 301.

  The light receiving unit is configured by integrating three light receiving element arrays 305 arranged at predetermined intervals in the optical axis direction.

A combination of the optical sensor 303 and the optical scale 301 is used as an optical encoder. The light receiving element array 305 outputs, for example, a two-phase sine wave signal (sine wave signal) by receiving the interference light irradiated from the light emitting unit of the optical sensor 303 and reflected by the optical scale 301.

  Note that the sine wave signal is not necessarily limited to two phases, and there may be three or more phases. However, in the following description, a case where position detection is performed using a two-phase sine wave signal will be described.

  In FIG. 1, a two-phase sine wave signal output from the optical sensor 303 is amplified by amplifiers 306a and 306b and taken into a microcomputer 307 serving as position detecting means. The microcomputer 307 obtains the current position of the lens 201 by performing input signal correction processing, interpolation calculation, and the like. Then, a position control calculation for moving the lens 201 to the target position is performed, and a drive signal is output to the drive circuit 308.

  The drive circuit 308 drives the lens drive motor 203 based on the drive signal from the microcomputer 307 to move the lens 201 to the target position.

  Here, a specific configuration of the microcomputer 307 will be described.

  The sample hold circuits 401a and 401b sample the signals amplified by the amplifiers 306a and 306b. The A / D converter 402 converts the output signals (analog signals) of the sample hold circuits 401a and 401b into digital signals.

  The lens position calculation unit 403 obtains the current position of the lens 201 by performing correction processing, interpolation calculation processing, and the like on the output signal of the A / D converter 402. The position control calculation unit 404 performs position control calculation for moving the lens 201 to the target position based on the calculation result in the lens position calculation unit 403. Specifically, the amount of movement of the lens 201 from the current position to the target position is obtained.

  The autofocus processing unit 406 obtains the position (target position) of the lens 201 at which the photographing optical system is in focus based on the signal from the image processing circuit 205, and outputs this position information to the position control calculation unit 404. .

  The drive signal generation unit 405 generates a drive signal corresponding to the calculation result in the position control calculation unit 404 and outputs it to the drive circuit 308.

  Note that the functions of the lens position calculation unit 403 and the position control calculation unit 404 can also be realized as software executed by a microcomputer instead of an electric circuit.

  The signal processing performed to detect the position of the lens 201 that is the position control object in the imaging apparatus of the present embodiment will be described with reference to FIG. First, when the lens 201 is at an arbitrary position within the movable range, the optical sensor 303 outputs a two-phase signal of a sine wave and a cosine wave corresponding to the current position of the lens 201.

  The microcomputer 307 performs gain adjustment and offset adjustment on the output signal of the optical sensor 303 by using the above-described mathematical expressions (1) to (3). As a result, two-phase signals (sine wave signals having different phases) having the same amplitude as shown in FIG. 3A are obtained.

  Subsequently, as shown in FIG. 3B, by inverting the positive / negative of each phase signal, four-phase (SIN, COS, -SIN, -COS) signals are generated. Select a phase that has a signal component with excellent linearity. Here, since the four phases each have a phase difference of 90 °, as shown in FIG. 3C, the selected phase is switched every time the lens 201 moves by the phase of 90 °.

  Then, as shown in FIG. 3D, each time the selected phase is switched, the signal component is shifted by the gain of the corresponding signal component, thereby linearly corresponding to the position of the lens 201. Obtain the result (location information). Using this position calculation result, the position of the lens 201 is detected based on the voltage value of the signal at the current position.

  As described above, by detecting the current position of the lens 201 and configuring the feedback system that drives the lens 201 based on the detection result, position control based on position detection by the optical encoder becomes possible.

  For the target position to move the lens 201, for example, the focus level of the captured image is determined by the microcomputer 307 from the output signal of the image processing circuit 205, and the autofocus processing unit 406 is based on a known focus control algorithm. Then, it is determined by calculating a lens position at which the photographing optical system is in focus as a target position.

  As an example of such a control method, a so-called hill-climbing method that detects the peak of the high-frequency component of the signal output from the image processing circuit 205 and controls the driving of the lens 201 is used. Specifically, the lens 201 is moved little by little to find a direction in which the high-frequency component increases, and further, the lens 201 is moved while setting the target position in that direction. If the high-frequency component changes from increase to decrease, the peak is reached. The lens 201 is returned to the vicinity, the target position is set again, and fine adjustment is performed to detect the peak.

  In the present embodiment, as the optical sensor 303, a light emitting unit and a light receiving unit that are integrally configured are used. However, a configuration in which the light emitting unit and the light receiving unit are separately provided may be used.

  In this embodiment, the light receiving element array 305 receives the reflected light from the optical scale 301. However, the light receiving element array 305 may be configured as described below. That is, the light irradiated from the light emitting part of the optical sensor can be transmitted through the optical scale (optical grating), and the transmitted light can be received by the light receiving part of the optical sensor.

  Further, in the above description, the optical scale 301 and the lens 201 are integrated with the optical sensor 303 and the lens barrel 202. However, the optical scale 301 and the optical sensor 303 are changed according to the movement of the lens 201. Any structure that moves relatively may be used.

  For example, the optical scale 301 can be fixed to the lens barrel 202 and the optical sensor 303 can be moved together with the lens 201.

  Next, the optical effective range (sometimes referred to as an imageable area) of the photographing optical system in the present embodiment will be described in detail below. The photographic optical system is designed to focus on a subject within a predetermined subject distance range (for example, 1 m to infinity), and accordingly, a moving range of the lens 201 necessary for focus adjustment is determined. Is done. This range is the optically effective range of the photographing optical system.

  FIG. 4 is a diagram for explaining the optical effective range in detail, and schematically showing the relationship between the subject distance and the position of the focus lens. As described above, the photographing optical system is generally composed of a plurality of lens groups, but here, for simplicity, a single lens 201 is schematically illustrated.

  Each lens group constituting the photographing optical system is configured by combining lenses having various shapes such as a convex shape or a concave shape, and all or a part of the plurality of lens groups can be used as a position control object. In this embodiment, a focus lens (lens 201) that performs focus adjustment is used as a position control object.

  FIG. 4A shows a state in which an image of a subject at a separation distance (subject distance) of, for example, 1 m is in focus on the imaging surface of the imaging element 204, and the lens 201 at this time is positioned at the position A. is there. FIG. 4B shows a state where an image of a subject at an infinite distance (subject distance), that is, an image of substantially parallel rays is in focus. It is at position B on the middle right side (that is, on the image sensor 204 side).

  On the other hand, in FIG. 4C, the lens 201 is at the position C on the right side of the position B, but in this state, the subject at any subject distance is not in focus.

  For this reason, in terms of optical design, the moving position of the lens 201 may be controlled within the range between the position A and the position B, and this range becomes the optically effective range. On the other hand, the position C is outside the optically effective range (outside the imageable region), and controlling the position of the lens 201 outside the optically effective range does not make optical meaning substantially. That is, it is not necessary to move the lens 201 outside the optically effective range in the focus control of the imaging apparatus.

  In the optical effective range (first movement range), it is necessary to detect and control the position of the lens with high accuracy, whereas in the range other than the optical effective range (second movement range), the accuracy is high. Even if it falls, it does not affect the performance as an imaging device, or even if it is affected, it is extremely small.

  Based on the above, the setting position of the origin on the optical scale 301, which is a feature of the present invention, will be described.

  FIG. 5 is a diagram illustrating an output signal of the optical sensor 303 when a discontinuous region having different optical characteristics (reflectance and transmittance) is provided at a position that can be the origin position in the optical scale 301. The output signal of the optical sensor 303 has a plurality of phases, but only one phase is shown here for the sake of simplicity.

In FIG. 5, the horizontal axis indicates the position of the lens 201 in the optical axis direction, and the vertical axis indicates the amplitude of the output signal from the optical sensor 303. The position P shown in FIG. 5 corresponds to the origin position, and the amplitude of the output signal decreases in the region C including the position P. That is, in the region C, the amplitude of the output signal decreases from the end of the region C toward the position P. Based on this change in amplitude, the origin position can be detected.

On the other hand, in the lens position in the region B in FIG. 5, and far enough away from the position P, the amplitude of the output signal is constant.

  Therefore, the lens 201, the optical scale 301, and the optical sensor 303 are arranged so that the area A in FIG. 5 is the movable range of the lens 201 and the area B in FIG. 5 is the optically effective range of the photographing optical system. To do.

  With this configuration, the amplitude of the output signal from the optical encoder is constant within the optically effective range, and the position detection and position control of the lens 201 can be performed with high accuracy.

On the other hand, the amplitude of the output signal decreases in the vicinity of the origin position P, and therefore the position detection accuracy may be reduced if the above-described calculation processing is performed. However, the detection of the origin position may be performed only when the imaging apparatus is started, for example, and as described above, the lens 201 is moved outside the optically effective range (a region other than the region B in FIG. 5) during the photographing operation . Since this is not necessary, this decrease in position detection accuracy does not affect the performance of the imaging apparatus.

  The flow of position control of the lens 201 performed using the processing method and configuration described in detail so far will be briefly described with reference to FIG.

  First, the lens 201 is moved to the rear end in the second movement range when, for example, the imaging apparatus is turned on or activated, or when the operator performs a predetermined operation on the operation unit of the imaging apparatus. For example, the origin position is detected while gradually moving forward (step S501).

  At this time, for example, referring to FIG. 5, the origin position is detected by detecting a point where the signal from the optical sensor 303 is highly reproducible, for example, a point that intersects the central axis in the signal after the gain and offset are corrected. Set to the origin position.

  When the origin position is detected in this way, the lens 201 is moved to the optically effective range (first movement range) (step S502). Whether or not the lens 201 is positioned within the optically effective range is determined by performing the above-described position calculation using the detected origin position as a reference position.

  When the imaging apparatus completes the activation process and the autofocus operation is started, the current position of the lens 201 is detected by the above-described position calculation using the detected origin position as a reference position (step S503). The degree of focus is determined using the output signal of the image sensor 204, and the target position of the lens 201 is set (step S504).

  The movement amount of the lens 201 is set based on the current position and the target position, and the lens 201 is moved to the target position based on the set value (step S505).

According to the present embodiment, a sine wave signal from the optical encoder (optical sensor 303) is processed to detect the current position of the lens 201, and a discontinuous region 302a is provided in the optical scale 301 of the optical encoder to provide an origin. The position is detected. The origin position (discontinuous region 302a) is positioned outside the optically effective range.

  Thereby, it is possible to prevent the performance of the image pickup apparatus from being deteriorated due to a decrease in the lens position control accuracy near the origin position.

In the present embodiment, an area for generating a signal that continuously changes at a predetermined period and an area for generating a discontinuous signal including a signal component different from the period are formed on the surface of the optical scale 301. Both the periodic signal generation unit and the discontinuous signal generation unit are formed in the formed configuration, that is, the common optical scale 301. Note that the periodic signal generation unit and the discontinuous signal generation unit may be formed on separate optical scales .

Furthermore, optical scale 301 may not be formed in a straight line, it is possible to select the shape according to the movement path of the position置制your object.

In the present invention, as long as it outputs a sine wave signal it may not be an optical encoder, for example, may be a magnetic encoder.

  The magnetic encoder, for example, magnetizes the scale extending along the moving direction of the lens 201 so as to have opposite polarities alternately, and further provides an MR sensor as a magnetoresistive element facing the surface of the scale. Can be configured.

  Also in this case, when the lens 201 moves, a multi-phase sine wave signal is output from the MR sensor. Therefore, it is possible to perform highly accurate position control of the lens 201 by performing signal processing in the same manner as described above. it can.

  In this case, for example, a region where the magnetizing intensity of the scale is lowered (corresponding to the discontinuous region 302a) is provided in a part of the scale, and the output of the MR sensor changes discontinuously (changes the amplitude of the output signal) in this region. By doing so, the origin position can be detected as in the present embodiment.

  According to this embodiment, the origin position can be easily detected, and the absolute position of the lens 201 can be detected with high accuracy. In addition, since the optical scale 301 is provided with a plurality of optical gratings 302 used for detecting the absolute position and a plurality of optical gratings 302 used for detecting the origin position, each position is detected. Therefore, it is possible to reduce the size and the cost as compared with the case where the respective members are provided.

  On the other hand, in the present embodiment, as described above, the lens-integrated camera (optical device) has been described. However, in a camera system including a camera body and a lens device attached to the camera body, the lens device ( A position control device can be provided in the optical device.

It is a figure which shows embodiment at the time of applying the position control apparatus of this invention to the lens position control of an imaging device. It is a figure which shows the optical encoder of the said position control apparatus. It is a figure which shows the process sequence of the signal from the said optical encoder. It is a figure which shows typically the relationship between a to-be-photographed object distance and a focusing lens position. It is a figure which shows the setting position of the origin on a scale. It is process drawing which shows the outline of the flow of lens position control. It is a figure which shows the detection means of the origin position in a prior art. It is a figure which shows the example of the output signal of an encoder in the state which provided the optical discontinuity part used as the origin position on a scale. It is a figure which shows the state before the correction process of the amplitude of an encoder output data, and an amplitude center. It is a figure which shows the state after the correction process of the amplitude of an encoder output data, and an amplitude center.

Explanation of symbols

DESCRIPTION OF SYMBOLS 201 Lens 202 Lens tube 203 Image pick-up element 204 Image processing circuit 205 Lens drive motor 301 Optical scale 302 Optical grating 302a Discontinuous area 303 Optical sensor 305 Light receiving element array 307 Microcomputer 308 Drive circuit

Claims (9)

A scale on which a periodically changing pattern is formed, an encoder that outputs a sinusoidal signal by moving relative to the scale according to the movement of the position control object, and a position of the position control object. Control means for controlling,
The scale has a first region configured to make the amplitude of the output signal of the encoder constant, and a second region configured to change the amplitude of the output signal of the encoder,
The position control object is a lens of a photographing optical system, and the first region is a region corresponding to an optically effective range of the photographing optical system in which the lens can move during photographing.
The control means detects an origin position in the position control of the position control object based on an output signal of the encoder generated by the second area, and uses the detected origin position to control the position control. A position control device for detecting an absolute position of an object. The scale is an optical scale on which a pattern in which optical characteristics change periodically is formed,
The position control according to claim 1, wherein the encoder includes a light emitting unit that irradiates light to the optical scale, and a light receiving unit that receives light from the light emitting unit via the optical scale. apparatus.   The first region in the optical scale is a part formed by arranging a plurality of optical gratings having a predetermined transmittance or reflectance, and the second region in the optical scale is in the first region. The position control device according to claim 2, wherein the position control device is a portion formed by arranging optical gratings having transmittance or reflectance different from the optical grating. The scale is a magnetic scale on which a pattern in which magnetic characteristics change periodically is formed,
The position control device according to claim 1, wherein the encoder is a magnetic encoder having a magnetoresistive portion provided to be movable relative to the magnetic scale. Moving means for moving the position control object;
5. The position according to claim 1, wherein the control unit moves the position control object to a target position via the moving unit based on the detected absolute position. Control device.   The control unit detects an absolute position of the position control object based on data obtained by correcting the output signal using information on an amplitude and an amplitude center of the output signal of the encoder. The position control device described. The lens position control device according to any one of claims 1 to 6, characterized in that the focusing lens to perform focus adjustment of the plurality of lenses constituting the imaging optical system. Optical apparatus comprising the position control device according to any one of claims 1 to 7. A scale on which a periodically changing pattern is formed; and an encoder that outputs a sinusoidal signal by moving relative to the scale in accordance with the movement of a position control object; and the scale includes the encoder Used in a position control device having a first region configured to make the output signal amplitude constant and a second region configured to change the amplitude of the output signal of the encoder, A position control method for controlling the position of a position control object,
The position control object is a lens of a photographing optical system, and the first region is a region corresponding to an optically effective range of the photographing optical system in which the lens can move during photographing.
A first step of detecting an origin position in position control of the position control object based on an output signal of the encoder generated by the second region;
And a second step of detecting an absolute position of the position control object using the origin position detected in the first step.

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